How many pixels do I need?

If you want to take normal holiday snaps and family photos, the number of pixels in a modern digital camera is irrelevant.

You can stop reading there, if you want to, but if you want more details, you can go on.

All modern digital cameras have more pixels than you will need. The lowest number of pixels of any camera in the 2008 catalogue of fnac is 6 million, and that is a DSLR. Among the compact cameras that fit in your pocket, you do not find anything below 7 million pixels. With 6 million pixels you can print on A4 size without much problem. You can stretch it to about A2 format (42 × 59.4 cm) with acceptable quality.

With 12 million pixels, like the D300, one has enough to easily print out a high quality picture the size of an A4. Stretching it and accepting lower detail, one can get a decent print out the size of an A1 (59.4 × 84.1 cm). One can, of course, ask oneself how many A1-size pictures one will ever print out, and where one would put them.

Usually one says that high quality print is 300 dpi (dots per inch). To see how big a picture you can print with a certain image size, just divide the dimensions by 300. (And then multiply by 2.54 to get it in centimetres.)

(Width of image file in pixels) / 300 * 2.54 = (Width of high quality print out)

As a comparison, and A4 printed at 300 dpi contains 8,739,900 pixel, and a North American Letter size photo contains 8,415,000 pixel.

And what if you you do not want to print your pictures? If you just want to show them on computer screens?

Let's say you buy Apple's biggest Cinema Display that is 30 inches. To fill out every pixel of that screen you need no more than 4 million pixels - that is less than the worst digital camera you can buy today.


What is much more important than the number of pixels is the quality of the camera, the lens, the autofocus, the sensor and all that. If you compare the specifications of a DSLR with a digital compact camera, it is very possible that the compact camera has better specifications. However, when it comes to clarity and picture quality, the DSLR is almost always far superior.


A higher number of pixels may even make the picture worse. Let's say, that 6 million pixel sensors fit on a certain space in your camera. If you buy another camera the same space for sensors, but the number of sensors is 12 million, clearly each sensor is smaller in the 12 million pixel camera. Unfortunately a smaller sensor is also more sensitive to electric noise in the camera, so they are slightly more likely to register wrong values. This is especially visible with low light conditions and high ISO values. The result is noise, lighter dots, on the image. All cameras show noise under some conditions, but high pixel cameras have more noise than low pixel cameras.


Is there then no reason for a multitude of pixels? Oh, yes there is.

One is obviously if one really does want to print large highly detailed photos.

Another is if one crops a lot. In some conditions, like if one takes pictures of flying birds or fast cars, it may be difficult to target the camera right at the subject. One solution may be to use less zoom, take a picture of a larger area, and then crop it afterwards. If one does not have enough pixels to start with, this may turn out quite difficult.


There is just one main device one should avoid when taking holiday pictures, and that is the camera in a mobile phone. Currently none of them has any acceptable quality. It is very convenient to have a camera in one's phone. One always carries it around anyhow. However, in most cases the pictures that come out of it are not pictures one will be happy to look at in the future.